| Abstrakt: |
Persons with central nervous system (CNS) pathologies select low walking velocities, which limit functional ambulation. We've shown (Metabol 54:793, 2005) that healthy adults adopted a preferred walking speed (PWS) which relied primarily on fat oxidation for energy. Walking faster than PWS resulted in abrupt increases in carbohydrate oxidation. The purpose of this study was to determine if persons with CNS pathologies conform to this same pattern. Eight overnight-fasted individuals with various CNS pathologies (e.g. stroke, cerebral palsy, spinal cord injury, traumatic brain injury) walked overground at three self-determined speeds: preferred, slow, and fast. Rates of O2 consumption and CO2 production were measured, and net fuel oxidation rates were estimated using indirect calorimetry. Results revealed a) primary fuel sources of fat at slow and preferred speeds (34.4 ± 4.2 and 46.2 ± 7.0 m/min) and carbohydrate at fast speeds (56.1 m/min ± 10.5); b) a wide disparity in speeds across subjects (mean CV = 32.1%) despite similar % contributions of fat and carbohydrate (mean CV = 0.4%); c) low fat oxidation rates at the PWS compared to healthy adults (21.0 ± 9.9 vs 41.3 ± 3.7 cal kg-1 min-1). We propose that fuel selection may contribute to the selection of PWS in persons with CNS pathologies, and that limited fat oxidizing capacity prevents a higher, more functional, PWS. [ABSTRACT FROM AUTHOR] |
Plný text